Measuring alignment of the hindfoot.

In subtalar arthrodesis operations, correction of the hindfoot alignment is performed in about half of the cases. To improve the quality of the operation, a measurement system was developed which reliably measures the hindfoot angle pre-, per-, and postoperatively. This device was evaluated by measuring subjects in standing weightbearing position and in prone nonweightbearing position. The results were compared with hindfoot angles constructed on posterior photographic images. The results are similar to other studies (all maximum values): intratester accuracy 1.4 degrees, intertester accuracy 2.2 degrees, intratester reliability 0.9, and intertester reliability 0.74. The proposed device will improve the quality of correction, because it enables peroperative measurement of hindfoot alignment.